• Journal of the Korean Society of Physical Medicine
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• v.8 no.3
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• pp.387-395
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• 2013

PURPOSE: The purpose of the present study was to investigate the effect of the training using Pedalo equipment on balance function in post-stroke patients. METHODS: The present study was case-series. Ten post-stroke patients participated in the study. Participants performed the training using Pedalo equipment. The training using four Pedalo equipment lasted 30 minutes, 3 times a week for 6 weeks. Force platform, Berg Balance Scale(BBS), and Timed Up and Go(TUG) test were used to assess balance ability before and after training. RESULTS: After training using Pedalo equipment, there were significantly improved on path length and sway velocity of post-stroke patients in the both of eye open and - close conditions comparing with baseline. Also, on the BBS and TUG, there were significant improvements after training. CONCLUSION: The results of this study showed that the training using Pedalo equipment may be effective on improving the balance ability in the post-stroke patients. Through this study, we were able to confirm the potential of training using Pedalo equipment as an intervention in the rehabilitation of post-stroke patients.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.2
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• pp.224-230
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• 1999

Agglomeration of colloidal alumina particles in a suspension is simulated. Particles in a suspension have potential energies between them and move to decrease the summation of all the potential energies between particles. The effects of various types of potential curves on particle agglomeration were checked. Strong short range attractive energy without repulsive energy barrier makes small strong clusters with disordered network structure but weak short-range force with big repulsive energy barrier makes big agglomerates with a close packing structure. As particles are agglomerated the potential energy with strong repulsive energy barrier between agglomerates gradually decreases the importance of the repulsive energy barrier and induces a different type of agglomeration behavior.

• Computers and Concrete
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• v.21 no.2
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• pp.127-137
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• 2018

In this study, the behavior of the number of anchorage bolts on the glass-fiber reinforced polymer (GFRP) plates adhered to the surfaces of reinforcing concrete (RC) T-beams was investigated analytically. The analytical results were compared to the test results in term of shear strength, and midpoint displacement of the beam. The modelling of the beams was conducted in ABAQUS/CAE finite element software. The Concrete Damaged Plasticity (CDP) model was used for concrete material modeling, and Classical Metal Plasticity (CMP) model was used for reinforcement material modelling. Model-1 was the reference specimen with enough sufficient shear reinforcement, and Model-2 was the reference specimen having low shear reinforcement. Model-3, Model-4 and Model-5 were the specimens with lower shear reinforcement. These models consist of a single variable which was the number of anchorage bolts implemented to the GFRP plates. The anchorage bolts of 2, 3, and 4 were mutually mounted on each GFRP plates through the beam surfaces for Model-3, Model-4, and Model-5, respectively. It was found that Model-1, Model-3, Model-4 and Model-5 provided results approximately equal to the test results. The results show that the shear strength of the beams increased with increasing of anchorage numbers. While close results were obtained for Model-1, Model-3, Model-4 and Model-5, in Model-2, the rate of increase of displacement was higher than the increase of load rate. It was seen, finite element based ABAQUS program is inadequate in the modeling of the reinforced concrete specimens under shear force.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.262-273
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• 1991

In the present study, the steady, incompressible, isothermal, developing flow in a 90.deg. rectangular cross sectional strongly curved duct with aspect ratio 1:1.5 and Reynolds number of 9.4*10$^{4}$ has been investigated. Measurements of components of mean velocities, pressures, and corresponding components of the Reynolds stress tensor are obtained with a hot-wire anemometer and pitot tube. In general, flow in a curved duct is characterized by the secondary vortices which are driven mainly by centrifugal force-radial pressure gradient imbalance, and the stress field stabilizing effects near the convex wall and destablizing effects close to the concave wall. It was found that the secondary mean velocities attain values up to 39% of the bulk velocity and are largely responsible for the convections of Reynolds stress in the cross stream plane. Therefor upstream of the bend the Reynolds stress are low. Corresponding to the small boundary layer thickness. At successive planes, large values of Reynolds stress were observed near the concave surface and the side wall.

• Tunnel and Underground Space
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• v.8 no.1
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• pp.8-16
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• 1998

The first purpose of this study is to verify the application of computer modelling to a enclosed space fire. The second one is to determine temperature distribution for the three different ventilation types in case of a enclosed space fire. The third one is to find out the ventilation direction and ventilation quantity to remove effectively heat and combustion products generated by a fire in variable air volume(VAV) system. Firstly, compared with experimental results of Lawrence Livermore National Laboratory(LLNL), numerical results show good agreements. Secondly, among three different ventilation types, the numerical analyses show the highest temperature distribution in occupied zone(up to 1.8 m from bottom) from firing moment to 100 sec. when supply ducts are placed in ceiling and extract duct is placed close to the bottom on side walls. This is due to disadvantageous position of extract duct in ventilating high temperature air which rise because of buoyancy force. Thirdly, this study finds out effective ventilation direction and ventilation quantity to remove heat and combustion products generated by a fire by using VAV system. $CO_2$ concentration is used as a fire fume removal index. As soon as a fire happens, ventilation direction is changed in order to gather and drive out fire fumes. In case of three times ventilation quantity of ordinary one, $CO_2$ concentration and temperature have begun to decrease at 120 sec. after firing, i.e.fire fumes have begun to be removed.

• Korean Journal of Applied Biomechanics
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• v.15 no.1
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• pp.143-153
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• 2005

J.Y. CHOI,S. J. KIM, E. L. LEE. Change of plantar pressure Distribution of Open Stance during Forehand Strke in Tennis. Korean Journal of Sport Biomechanics, Vol. 15, No. 1, PP. 143-153, 2005. Recently among several tennis techniques forehand stroke has been greatly changed in the aspect of spin, grip and stance. The most fundamental factor among the three factors is the stance which consists of open, square and close stance and it is very important to know the patterns of plantar pressure distribution for the better understanding of forehand stroke. Therefore, the purpose of this study was to investigate the change of plantar pressure distribution in open stance during forehand stroke in tennis. Three high school tennis players were recruited for the study and required to perform forehand stroke five consecutive trials in the condition of open stance. The forehand strokes were filmed with two digital video cameras and measured with pedar system for plantar pressure. The plantar regions under the foot were divided into 3 regions, which were forefoot, midfoot, and rear foot. In conclusion, The plantar pressure of open stance during forehand stroke was distributed more largely to the right foot. The plantar pressure of open stance during forehand stroke was distributed more weight loads on forefoot of right than heel of right

• Korean Journal of Materials Research
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• v.15 no.5
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• pp.285-292
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• 2005

Anti-reflection film was coated by using spherical silica nano colloids. Silica colloid sol was reserved between two inclined slide glasses by capillary force, and particles were convectively stacked to form a film onto the substrate as the water evaporates. As the sliding speed increased, the thickness of the film decreased and the wavelength at the maximum transmittance decreased. The microstructure observed by SEM showed that silica particles were nearly close packed, which enabled the calculation of the effective refractive index of the film. The film thickness was measured by proffer and calculated from the wavelength of maximum transmittance and the effective refractive index. The effective refractive index of the film could be controlled by a subtle controlling of the coating speed and by mixing two different sized silica particles. When the 100 nm and 50 m particles were mixed at 4:1-5:1 volume ratio, the maximum transmittance of $95.2\%$ for one-sided coating was obtained. This is the one that has increased by $3.8\%$ compared to bare glass substrate, and shows that $99.0\%$ of transmittance or $1.0\%$ of reflectance can be achieved by the simple process if both sides of the substrate are coated.

• Korean Journal of Materials Research
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• v.21 no.3
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• pp.156-160
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• 2011

FePt nanoparticles suspension was synthesized by reduction of platinum acetylacetonate and decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine. FePt nanoparticles were coated on a substrate by convective assembly from the suspension. To prevent the coalescence during the annealing of FePt nanoparticles double convective coatings were tried. First convective coating was for silica particle assembly on a silicon substrate and second one was for FePt nanoparticles on the previously coated silica layers. It was observed by scanning electron microscopy (SEM) that FePt nanoparticles were dispersed on the silica particle surface. After annealing at $700^{\circ}C$ for 30 minutes under nitrogen atmosphere, FePt nanoparticles on silica particles were maintained in a dispersed state with slight increase of particle size. On the contrary, FePt nanoparticles that were directly coated on silicon substrate showed severe particle growth after annealing due to the close-packing of nanoparticles during assembly. The size variation during annealing was also verified by X-ray diffractometer (XRD). It was suggested that pre-coating, which offered solvent flux oppose to the capillary force between FePt nanoparticles, was an effective method to prevent coalescence of nano-sized particles under high temperature annealing.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.5
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• pp.653-658
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• 2013

For towing the new type armored vehicle and maintaining the close support, the armored recovery vehicle(ARV) with winch and crane has been developed. In case of crane, it is mainly used to salvage heavy objects by rotational and vertical motion. Especially, the crane bracket is very important parts due to fixing the ARV's body and rotary joint and preventing the force rotation of crane. Therefore, the crane bracket needs to have an enough strength to endure the high load and it is very important to analyze the stress distribution under loads. In the present work, the experimental and analytical investigation on structural integrity evaluation of crane bracket were carried out. The simulation of three-dimensional finite element method(FEM) was compared with experimental datum. From the numerical results, the FEM simulations corresponded well with th experimental results and the structural safety was confirmed by safety factor.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.86-94
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• 2008

A total stroke of an opening or closing motion of a hinge mechanism in a folder-type mobile phone is composed of two portions. In the first portion, human fingers act a force to open or close the folder. In this portion, the rotating folder compresses the coil spring installed in the mechanism. In the last portion, this compressed coil spring generates a torque to rotate the folder. The main merit of this study is that we have designed a hinge mechanism to be operated by a uniform torque in the first portion of the total stroke. The uniform torque means that it is constant along the folder's swing angle. This mechanism will give softer feeling to human fingers. A pair of contours in the mechanism plays an important role. It transforms rotation into translation in the first portion; on the other hand, it transforms translation into rotation in the last portion. In this study, we have developed an algorithm to obtain the pair of contour curves. We divided the total contour curves into finite sub-intervals. Assuming that the curves in every sub-interval are parabolas, we have obtained the coefficients of them by solving systems of nonlinear equations recursively.